Spatial ultrasound modulator, ultrasonic apparatus having the same and method of generating amplitude-modulated ultrasonic waves using the same

The present application claims priority from Korean Patent Application No. 10-2023-0038738, filed on Mar. 24, 2023, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

The present disclosure relates to a spatial ultrasound modulator, an ultrasonic apparatus having the spatial ultrasound modulator and a method of generating amplitude-modulated ultrasonic waves using the spatial ultrasound modulator. More specifically, the present disclosure pertains to a dynamic spatial ultrasound modulator capable of shaping the wavefront of ultrasonic waves in real time using a plurality of capacitive micromachined ultrasonic transducers (CMUTs), an ultrasonic apparatus having the spatial ultrasound modulator and a method of generating amplitude modulated ultrasonic waves using the spatial ultrasound modulator.

Spatial ultrasonic modulators are widely used for non-destructive testing of a test target or non-invasive stimulation within a living organism that require directing ultrasonic waves into a target object without damaging the target object.

The conventional spatial ultrasound modulator includes a plurality of wave sources, each being driven by an individual driving source, and a plurality of ultrasonic waves having different phases are generated from the plurality of wave sources. Moreover, the spatial ultrasound modulator generates incident waves that are ultrasonic waves in which the generated plurality of ultrasonic waves are synthesized.

Recently, the spatial ultrasound modulators have been increasingly used in the fields where higher precision is required, such as neural stimulation technologies for stimulating fine nerves within the living organism or technologies for imaging of internal defect of ultraprecision integrated circuit devices. Therefore, technological development is required for a spatial ultrasound modulator capable of creating incident waves having a high focusing resolution.

The focusing resolution for the target region is determined by the focusing resolution of the spatial ultrasound modulator. Moreover, the focusing resolution of the spatial ultrasound modulator is determined by the number of individual wave sources that generate the ultrasonic waves.

Since the conventional spatial ultrasound modulator includes a driving unit for each wave source, the number of wave sources needs to be increased to improve the focusing resolution. In such a case, the number of driving sources for individually driving the wave sources is also increased. Accordingly, the device volume of the spatial ultrasound modulator is inevitably increased.

To address the aforementioned issues, there is a demand for a novel spatial ultrasound modulator and an ultrasonic apparatus having the same that offer high focusing resolution despite a small size.

Proposed to address the aforementioned issues, an object of the present disclosure is to provide a spatial ultrasound modulator in which an ultrasonic array including a plurality of ultrasonic generators superimposed on a plurality of pixels is configured to generate amplitude-modulated ultrasonic waves, of which the wavefront may be shaped in real time.

Another object of the present disclosure is to provide an ultrasonic apparatus including the aforementioned spatial ultrasound modulator.

Yet another object of the present disclosure is to provide a method of generating amplitude-modulated ultrasonic waves, of which wavefront may be shaped in real time, using the aforementioned spatial ultrasound modulator.

A spatial ultrasound modulator in accordance with an embodiment of the present disclosure may include a signal line, an ultrasonic array, a pixel coder and an ultrasonic driver.

The signal line may include a plurality of first conductive lines and a plurality of second conductive lines. The plurality of first conductive lines may be arranged to be spaced apart from each other on a substrate. The plurality of second conductive lines may be arranged to intersect the first conductive lines above the plurality of first conductive lines and to be spaced apart from each other.

The ultrasonic array may include a plurality of ultrasonic generators. Each of the plurality of ultrasonic generators may include at least one CMUT device. Each of the plurality of ultrasonic generators may be superimposed on any one of a plurality of pixels, which are intersection points of the plurality of first conductive lines and the plurality of second conductive lines. Each of the plurality ultrasonic generators may generate unit-ultrasonic waves.

The pixel coder may generate a coding array by determining the operation mode of each of the plurality of ultrasonic generators as either a normal mode or a pull-in mode. The coding array may include an active pixel and an inactive pixel.

The ultrasonic driver may drive the coding array to generate amplitude-modulated ultrasonic waves in which the wavefront may be transformed. The amplitude-modulated ultrasonic waves may have a plurality of unit-ultrasonic waves synthesized therein.

In the spatial ultrasound modulator in accordance with an embodiment of the present disclosure, the operation mode may be one of the normal mode and the pull-in mode. When the operation mode is in the normal mode, the ultrasonic generator may operate at a first natural frequency, and the pixel superimposed on the ultrasonic generator may function as an active pixel. When the operation mode is in the pull-in mode, the ultrasonic generator may operate at a second natural frequency different from the first natural frequency, and the pixel superimposed on the ultrasonic generator may function as an inactive pixel.

The ultrasonic generator of the spatial ultrasound modulator in accordance with an embodiment of the present disclosure may include a plurality of CMUT devices. The plurality of CMUT devices may generate a plurality of fine ultrasonic waves. The unit-ultrasonic waves may have the plurality of fine ultrasonic waves synthesized therein.

The pixel coder of the spatial ultrasound modulator in accordance with an embodiment of the present disclosure may include an initialization driver, a scanline setter, a mode line setter, a pull-in coder and a timing controller.

The initialization driver may apply an initialization signal to the plurality of first conductive lines and the plurality of second conductive lines to initialize the operation mode of the plurality of ultrasonic generators to the normal mode.

The scanline setter may select any one of the plurality of second conductive lines as a scan line. The scanline setter may select a pixel row corresponding to the scan line as a coding row.

The mode line setter may select at least one of the plurality of first conductive lines as a mode changing line. The mode line setter may select a pixel column of an ultrasonic array corresponding to the mode changing line as the coding row.

The pull-in coder may apply a scan signal to the scan line. The pull-in coder may apply a mode changing signal to the mode changing line. The pull-in coder may perform a pull-in coding operation to code a coding target pixel in the pull-in mode using the potential difference between the scan signal and the mode changing signal. The coding target pixel may be a pixel located at the intersection of a coding row and a coding column.

The timing controller may control operation timing of the scanline setter and the mode line setter to successively select one of the plurality of second conductive lines as a scan line. The timing controller may select the first conductive line of the plurality of first conductive lines corresponding to the coding target pixel as the mode changing line.

The initialization signal of the spatial ultrasound modulator in accordance with an embodiment of the present disclosure may include a first partial setting signal and a second partial setting signal. The first partial setting signal corresponding to a first partial setting voltage may be applied to the plurality of first conductive lines. The second partial setting signal corresponding to a second partial setting voltage may be applied to the plurality of second conductive lines. A setting voltage may be the potential difference between the first partial setting voltage and the second partial setting voltage. The setting voltage may satisfy the condition expressed in (1) below. The setting voltage may be applied to the ultrasonic generator.

Here, Vpo may be a pull-out voltage, and Vpi may be a pull-in voltage. Vs may be a setting voltage, whereas Vs1 may be the first partial setting voltage, and Vs2 may be the second partial setting voltage.

A scan voltage of the spatial ultrasound modulator in accordance with an embodiment of the present disclosure may be a voltage of the scan signal. A mode voltage may be a voltage of the mode changing signal. When the scan voltage and the mode voltage satisfy the below conditions (2) to (4), the operation mode of the ultrasonic generator superimposed on a coding target pixel among the ultrasonic generators superimposed on a coding row may be changed to the pull-in mode. The operation mode of the ultrasonic generator not corresponding to the coding target pixel among the ultrasonic generators superimposed on the coding row may be kept in the normal mode.

In conditions (2) and (4), Vs may be the setting voltage, and Vscan may be the scan voltage, and Vmode may be the mode voltage.

When the mode voltage of the spatial ultrasound modulator in accordance with an embodiment of the present disclosure satisfies condition (5), the operation mode of the ultrasonic generator superimposed on a pull-in pixel may be kept in the pull-in mode while the pull-in coding operation is performed in a coding row corresponding to the pull-in pixel. The pull-in pixel may be a pixel that has been already coded in the pull-in mode through the pull-in coding operation.Vpo<Vmode<Vpi  (5)

The pixel coder of the spatial ultrasound modulator in accordance with an embodiment of the present disclosure may further include a pixel reset unit configured to reset a coded pixel.

The ultrasonic driver of the spatial ultrasound modulator in accordance with an embodiment of the present disclosure may include a drive setting unit and a driving unit.

The drive setting unit may control the bias voltages applied to the plurality of ultrasonic generators of the coding array to be the same with each other by applying a drive-bias to the coding array.

The driving unit may control the ultrasonic generator corresponding to the active pixel to generate unit ultrasonic waves by applying a drive signal to the coding array.

The drive setting unit of the spatial ultrasound modulator in accordance with an embodiment of the present disclosure may apply a drive-bias satisfying the below condition (6) to the plurality of first conductive lines. The drive setting unit may control the plurality of second conductive lines to be grounded.Vpo<Vd<Vpi  (6)

Here, Vpo may be a pull-out voltage, and Vpi may be a pull-in voltage, whereas Vd may be a drive-bias.

The frequency of the drive signal of the spatial ultrasound modulator in accordance with an embodiment of the present disclosure may be the same as the natural frequency of the ultrasonic generator operating in the normal mode.

The spatial ultrasound modulator in accordance with an embodiment of the present disclosure may further include a waveform controller. The waveform controller may be configured to control the pixel coder to change the coding array according to wavefront information. The waveform controller may control the ultrasonic driver to generate amplitude-modulated ultrasonic waves according to the changed coding array to deform the wavefront of the amplitude-modulated ultrasonic waves in real time.

An ultrasonic apparatus in accordance with an embodiment of the present disclosure may include a wavefront information setter, a spatial ultrasound modulator and a response detection unit.

The wavefront information setter may be configured to set wavefront information corresponding to incident waves. The incident waves may be spatially modulated ultrasonic waves incident on a target object.

The spatial ultrasound modulator may include a pixel coder and an ultrasonic driver.

The pixel coder may be configured to code the ultrasonic array based on the wavefront information to generate the coding array. The coding array may include an active pixel and an inactive pixel. The ultrasonic array may include a plurality of ultrasonic generators. Each of the plurality of ultrasonic generators may include at least one capacitive micromachined ultrasonic transducer (CMUT) device. Each of the plurality of ultrasonic generators may be superimposed on any one of a plurality of pixels. The ultrasonic driver may be configured to drive the coding array to generate amplitude-modulated ultrasonic waves having a wavefront corresponding to the wavefront information.

The response detection unit may be configured to detect a response of the target object to the incident waves.

The spatial ultrasound modulator of the ultrasonic apparatus in accordance with an embodiment of the present disclosure may further include a signal line including a plurality of first conductive lines and a plurality of second conductive lines.

The plurality of first conductive lines may be arranged to be spaced apart from each other on a substrate. The plurality of second conductive lines may be arranged to intersect the plurality of first conductive lines above the plurality of first conductive lines and to be spaced apart from each other. The bias voltage applied to the ultrasonic generator may be a potential difference between any one of the plurality of first conductive lines and any one of the plurality of second conductive lines.

The pixel coder of the ultrasonic apparatus in accordance with an embodiment of the present disclosure may include an initialization driver, a scanline setter, a mode line setter, a pull-in coder and a timing controller.

The initialization driver may apply an initialization signal to the plurality of first conductive lines and the plurality of second conductive lines to initialize the operation mode of each of the plurality of ultrasonic generators to a normal mode.

The scanline setter may select any one of the plurality of second conductive lines as a scan line for transmitting a scan signal. The scanline setter may select a pixel row, which is the ultrasonic generators among the plurality of ultrasonic generators corresponding to the scan line, as a coding row.

The mode line setter may select at least one of the plurality of first conductive lines as a mode changing line for transmitting a mode changing signal. The mode changing signal may be for changing the operation mode of the ultrasonic generator to any one of the normal mode and the pull-in mode. The mode line setter may select a pixel column, which is the ultrasonic generators among the plurality of ultrasonic generators corresponding to the mode changing line, as the coding column.

The pull-in coder may apply the scan signal to the scan line. The pull-in coder may apply the mode changing signal to the mode changing line. The pull-in coder may perform a pull-in coding operation, which is configured to code a coding target pixel in the pull-in mode using the potential difference between the scan signal and the mode changing signal. The coding target pixel may be a pixel located at an intersection of a coding row and a coding column.

The timing controller may be configured to control the scanline setter to successively select each of the plurality of second conductive lines as the scan line. The timing controller may be configured to control the mode line setter to select the first conductive line of the plurality of the first conductive lines corresponding to the coding target pixel as the mode changing line. The timing controller may be configured to control the pull-in coder to perform the pull-in coding operation.

The initialization signal of the ultrasonic apparatus in accordance with an embodiment of the present disclosure may include a first partial setting signal and a second partial setting signal. The first partial setting signal corresponding to a first partial setting voltage may be simultaneously applied to the plurality of first conductive lines. The second partial setting signal corresponding to a second partial setting voltage may be simultaneously applied to the plurality of second conductive lines. A setting voltage may be the potential difference between the first partial setting voltage and the second partial setting voltage. The setting voltage may satisfy the condition expressed in (1) below. The setting voltage may be applied to the ultrasonic generator.

Here, Vpo may be a pull-out voltage, and Vpi may be a pull-in voltage. Vs may be a setting voltage, whereas Vs1 may be the first partial setting voltage, and Vs2 may be the second partial setting voltage.

A scan voltage may be a voltage of the scan signal. A mode voltage may be a voltage of the mode changing signal. When the scan voltage and the mode voltage satisfy the below conditions (2) to (4), a bias voltage greater than the pull-in voltage may be applied to the ultrasonic generator corresponding to the coding target pixel, resulting in changing the operation mode of the ultrasonic generator to the pull-in mode and maintaining the operation mode of the ultrasonic generator not corresponding to the coding target pixel in the normal

In conditions (2) and (4), Vs may be the setting voltage, and Vscan may be the scan voltage, and Vmode may be the mode voltage.

When the mode voltage satisfies condition (5), the operation mode of the ultrasonic generator superimposed on a pull-in pixel may be maintained in the pull-in mode while the pull-in coding operation is performed in a coding row corresponding to the pull-in pixel. The pull-in pixel may be a pixel that has been already coded in the pull-in mode through the pull-in coding operation.

The ultrasonic driver of the ultrasonic apparatus in accordance with an embodiment of the present disclosure may include a drive setting unit and a driving unit.

The drive setting unit may apply a drive-bias satisfying the below condition (6) to the plurality of first conductive lines. The drive setting unit may control the plurality of second conductive lines to be grounded.

Here, Vpo may be a pull-out voltage, and Vpi may be a pull-in voltage, whereas Vd may be a drive-bias.

The driving unit may control the ultrasonic generator corresponding to the active pixel to generate unit ultrasonic waves by applying a drive signal to the coding array.

The drive signal of the ultrasonic apparatus in accordance with an embodiment of the present disclosure may include an AC signal. The frequency of the AC signal may be the same as the natural frequency of the ultrasonic generator that is operating in the normal mode. The method of generating amplitude-modulated ultrasonic waves in accordance with an embodiment of the present disclosure may include step 1, step 2, step 3 and step 4.

In step 1, an ultrasonic array may include a plurality of pixel rows and a plurality of pixel columns. The pixel rows and the pixel columns may each include a plurality of ultrasonic generators. Each of the plurality of ultrasonic generators may be superimposed on any one of a plurality of pixels. An ultrasonic array may be initialized by a setting voltage such that the plurality of ultrasonic generators operate in a normal mode.

In step 2, the plurality of pixel rows may be successively selected, one by one, as a coding row. At least one pixel column of the plurality of pixel columns that corresponds to a coding target pixel may be selected as a coding column.

In step 3, a coding array may include an active pixel and an inactive pixel. When the operation mode is in the normal mode, the ultrasonic generator may operate at a first natural frequency, and the pixel superimposed on the ultrasonic generator may function as an active pixel. When the operation mode is in the pull-in mode, the ultrasonic generator may operate at a second natural frequency different from the first natural frequency, and the pixel superimposed on the ultrasonic generator may function as an inactive pixel. Every time a coding row is selected, a scan voltage and a mode voltage are applied to the coding row and the coding column, respectively, and the operation mode of the ultrasonic generator superimposed on the coding target pixel may be changed to the pull-in mode. Alternatively, the coding array may be created.

In step 4, the coding array may generate amplitude-modulated ultrasonic waves in which the wavefront may be modified. The amplitude-modulated ultrasonic waves may be a synthesized plurality of unit-ultrasonic waves, each of which is generated by an ultrasonic generator superimposed on an active pixel.

In step 1 of the method of generating amplitude-modulated ultrasonic waves in accordance with an embodiment of the present disclosure, the plurality of pixel rows may be grounded. A setting voltage satisfying the condition expressed in (1) below may be applied to a plurality of pixel columns.

Here, Vpo may be a pull-out voltage, and Vpi may be a pull-in voltage. Vs may be a setting voltage, whereas Vs1 may be a first partial setting voltage, and Vs2 may be a second partial setting voltage.

In step 3 of the method of generating amplitude-modulated ultrasonic waves in accordance with an embodiment of the present disclosure, when the setting voltage, the scan voltage and the mode voltage satisfy conditions (2) to (4) shown below, the operation mode of the ultrasonic generator of the plurality of ultrasonic generators superimposed on the coding row that is not superimposed on the coding target pixel may be maintained in the normal mode.

In conditions (2) and (4), Vs may be the setting voltage, and Vscan may be the scan voltage, and Vmode may be the mode voltage.

When the mode voltage of the method of generating amplitude-modulated ultrasonic waves in accordance with an embodiment of the present disclosure satisfies condition (5), the operation mode of the ultrasonic generator superimposed on a pull-in pixel may be kept in the pull-in mode while the pull-in coding operation is performed for a coding row corresponding to the coding target pixel. The pull-in pixel may be a pixel that has been already coded in the pull-in mode through the pull-in coding operation.

The method of generating amplitude-modulated ultrasonic waves in accordance with an embodiment of the present disclosure may further include step 3-1, in which the coding row may be grounded. Moreover, a drive-bias satisfying condition (6) expressed below may be applied to a coding column such that the operation mode of the ultrasonic generator superimposed on the pull-in pixel may be maintained in the pull-in mode. Step 3-1 may be carried out after step 3 and before step 4. The pull-in pixel may be a pixel that has been coded in the pull-in mode through the pull-in coding operation.

Here, Vpo may be a pull-out voltage, and Vpi may be a pull-in voltage, whereas Vd may be a drive-bias.

In step 4 of the method of generating amplitude-modulated ultrasonic waves in accordance with an embodiment of the present disclosure, a drive signal may be applied to the coding array. Moreover, the drive signal may be an AC signal having the same frequency as the first natural frequency.

According to an embodiment of the present disclosure, it is possible to provide a spatial ultrasound modulator in which an ultrasonic array including a plurality of ultrasonic generators superimposed on a plurality of pixels generate amplitude-modulated ultrasonic waves, of which wavefront may be shaped in real time, an ultrasonic apparatus including the spatial ultrasound modulator and a method of generating amplitude-modulated ultrasonic waves using the spatial ultrasound modulator.

The plurality of ultrasonic generators may be coded with one of the normal mode and the pull-in mode to generate a coding array. Each of the plurality of ultrasonic generators may include at least one CMUT device. The ultrasonic array may include a plurality of ultrasonic generators, each of which is superimposed on any one of a plurality of pixels. The coding array may include an active pixel and an inactive pixel.

When a drive signal having the same frequency as the natural frequency of the ultrasonic generator operating in the normal mode is applied to the coding array, unit-ultrasonic waves may be generated in the active pixels only, and the unit-ultrasonic waves may not be generated in the inactive pixels. That is, a plurality of amplitude-modulated ultrasonic waves having different shapes of wavefront may be generated based on a pixel map.

The operation mode of the plurality of ultrasonic generators of the coding array may be changed based on the scan voltage, the mode voltage and the setting voltage. Therefore, users may readily change the coding array by changing the scan voltage, the mode voltage and/or the setting voltage. In other words, with the present disclosure, the shape of the wavefront of the amplitude-modulated ultrasonic waves may be changed by changing the scan voltage, the mode voltage and/or the setting voltage. Moreover, increasing the degree of integration of the ultrasonic generators may improve the focusing resolution.

Hereinafter, certain preferred embodiments of the present disclosure will be described with reference to the accompanied drawings, but the described embodiments are not intended to limit the present disclosure thereto, and anyone of ordinary skill in the art to which the present disclosure pertains shall be able to embody the present disclosure in various other forms without departing from the technical ideas of the present disclosure.

In the accompanied drawings, the dimensions of substrates, layers (or membranes), areas, patterns or structures are exaggerated for the sake of clarity of the present disclosure. In the present disclosure, when a substrate, layer (or membrane), area, pattern or structure is described to be formed “on,” “above” or “below” the other substrate, layer (or membrane), area, pattern or structure, such a substrate, layer (or membrane), area, pattern or structure may be formed directly on, above or below the other substrate, layer (or membrane), area, pattern or structure, or another substrate, layer (or membrane), area, pattern or structure may be additionally formed on the other substrate, layer (or membrane), area, pattern or structure. Moreover, terms such as “first,” “second” and “third” used to describe materials, layers (or membranes), areas, electrodes, patterns or structures are not intended to limit these members to these terms but to distinguish the materials, layers (or membranes), areas, electrodes, patterns or structures from each other. Accordingly, the terms such as “first,” “second” and “third” may be used selectively or interchangeably for each of the materials, layers (or membranes), areas, electrodes, patterns or structures.

1 FIG. 2 FIG.A 1 FIG. 2 FIG.B 1 FIG. 3 FIG. 1 FIG. 1000 1000 1000 1000 is an exemplary illustration of a spatial ultrasound modulatorin accordance with an embodiment of the present disclosure.illustrates a sectional view of the spatial ultrasound modulatorshown inalong the I-I′ line, andillustrates a sectional view of the spatial ultrasound modulatorshown inalong the II-II′ line.illustrates a top view of an ultrasonic array of the spatial ultrasound modulatorshown in.

1 FIG. 3 FIG. 1000 100 200 300 400 500 600 Referring toto, the spatial ultrasound modulatorin accordance with an embodiment of the present disclosure may include a substrate, a signal line, an ultrasonic array, a pixel coder, an ultrasonic driverand a waveform controller.

200 210 220 210 220 100 100 The signal linemay include first conductive linesand second conductive lines. The first conductive linesand the second conductive linesmay be arranged to intersect each other along a third direction (z) on the substrate. The third direction (z) may be perpendicular to an upper surface of the substrate.

300 390 390 210 220 4 FIG. The ultrasonic arraymay include a plurality of ultrasonic generators(see). Each of the plurality of ultrasonic generatorsmay be superimposed on any one of a plurality of pixels P, which are intersections of the plurality first conductive linesand the plurality of second conductive lines.

400 300 301 400 390 390 7 FIG. The pixel codermay be configured to code the ultrasonic arrayto generate a coding array(see). That is, the pixel codermay code the plurality of ultrasonic generatorsthat are superimposed on the plurality of pixels P. In this description, “coding” refers to a process in which the operation mode of an ultrasonic generatorsuperimposed on a certain pixel P is changed. For example, when it is described that a pixel is coded or an ultrasonic generator is coded, it may be interpreted that the operation mode of the ultrasonic generator superimposed on the pixel is changed.

301 7 FIG. 7 FIG. 7 FIG. The coding array(see) may include an active pixel AP (see) and an inactive pixel IAP (see).

500 301 7 FIG. The ultrasonic drivermay be configured to drive the coding arrayto generate amplitude-modulated ultrasonic waves AMU (see).

600 The waveform controllermay be configured to change the shape of the waveform of the amplitude-modulated ultrasonic waves AMU in real time.

1000 1000 In an embodiment of the present disclosure, the spatial ultrasound modulatormay be configured to perform functions similar to those of a spatial light modulator (SLM), which is configured to shape the wavefront of light hologram. That is, the spatial ultrasound modulatormay be configured to shape the wavefront of the focused ultrasonic waves to meet the purpose.

100 1000 100 210 220 300 390 300 210 220 In an embodiment of the present disclosure, the substratemay be a structure constituting a base of the spatial ultrasound modulator. Moreover, placed on the substratemay be the first conductive lines, the second conductive linesand the ultrasonic array. The plurality of ultrasonic generatorsof the ultrasonic arraymay be interposed between the plurality of first conductive linesand the plurality of second conductive lines.

100 1000 100 For instance, the substratemay be used as a base substrate for performing a micro-electro mechanical system (MEMS) process for forming unit cells that constitute the spatial ultrasound modulator. Moreover, the substrateis made of a semiconductor material, such as silicon or gallium.

390 100 100 210 210 The plurality of ultrasonic generatorsmay be disposed on the substrate. Therefore, the substratemay be a useful semiconductor substrate for manufacturing the plurality of first conductive linesand the plurality of CMUT devices CM. The plurality of first conductive linesmay be for applying a drive signal. The CMUT devices CM may be a capacitive micromachined ultrasonic transducer (CMUT).

390 Each of the plurality of ultrasonic generatorsmay include at least one CMUT device CM. Since the CMUT device CM functions as a capacitor, the CMUT device CM may detect ultrasonic waves pursuant to charging and discharging electrical energy.

2 FIG.A 210 100 310 100 100 Referring to, in an embodiment of the present disclosure, the plurality of first conductive linesmay be interposed between one surface of the substrateand an insulation film. Moreover, the substratemay have a relatively high resistance. For example, the substratemay be a part of a silicon wafer.

100 100 100 500 210 220 100 The substratemay be rectangular. The substratemay have a length in a first direction (x) and a width in a second direction (y). The second direction (y) may be substantially perpendicular to the first direction (x). However, this is merely an example, and the shape of the substratemay be properly modified based on the shape of the ultrasonic driver. The plurality of first conductive linesand the plurality of second conductive linesmay be spaced apart in a third direction (z) on one side of the substrate. The third direction (z) may be perpendicular to the first direction (x) and the second direction (y).

210 100 210 210 210 The plurality of first conductive linesmay be disposed on the substrate. For instance, each of the plurality of first conductive linesmay extend along the first direction (x). Moreover, the first conductive linesmay be spaced apart along the second direction (y). Since an insulating layer (not shown) is interposed between adjacent first conductive lines, the adjacent first conductive lines may be insulated from each other. Accordingly, it is possible to prevent an interference between a plurality of mode changing signals applied to the plurality of first conductive lines.

440 390 440 390 210 220 6 FIG. A pull-in coder(see) may be configured to generate a mode changing signal for changing the operation mode of the ultrasonic generator. The pull-in codermay be configured to change the operation mode of the ultrasonic generatorcorresponding to a pixel P to which signals are simultaneously applied from any one of the plurality of first conductive linesand any one of the plurality of second conductive lines.

210 210 Therefore, each of the plurality of first conductive linesmay include a material having a low resistance to minimize a delay in signal transmission and signal conversion. For example, the first conductive linemay include any one of copper, aluminum and tungsten.

100 210 After the insulating layer (not shown) covering the substrateis formed, the insulating layer may be partially removed to form a plurality of trenches. Moreover, each of the plurality of trenches may extend in the first direction (x). Moreover, the plurality of trenches may be spaced apart at regular intervals along the second direction (y). Moreover, the plurality of trenches may be filled with a conductive material to form the plurality of first conductive lines.

1 FIG. 390 Referring to, the plurality of ultrasonic generatorsmay be spaced apart from each other at regular intervals along the second direction (y).

390 210 220 Moreover, certain ultrasonic generators of the plurality of ultrasonic generatorsmay be disposed to be adjacent to one of the plurality of first conductive linesand electrically connected to one of the plurality of second conductive lines.

390 210 220 Moreover, other ultrasonic generators of the plurality of ultrasonic generatorsmay be disposed to be adjacent to another one of the plurality of first conductive linesand electrically connected to another one of the plurality of second conductive lines.

220 210 220 220 210 Each of the plurality of second conductive linesmay be spaced apart from the plurality of first conductive linesand extend along the second direction (y). Moreover, the plurality of second conductive linesmay be spaced apart from each other along the first direction (x). Moreover, the plurality of second conductive linesmay be arranged to intersect the plurality of first conductive lines.

3 4 FIGS.and 390 210 220 390 210 220 390 300 100 Referring to, each of the plurality of ultrasonic generatorsmay be arranged to be superimposed on a pixel P that is an intersecting point between one of the plurality of first conductive linesand one of the plurality of second conductive lines. That is, the plurality of ultrasonic generatorsmay be electrically connected with one of the plurality of first conductive linesand one of the plurality of second conductive lines. Accordingly, the plurality of ultrasonic generatorsof the ultrasonic arraymay be superimposed on a plurality of pixels P arranged in a matrix shape along the first direction (x) and the second direction (y) on the substrate.

3 FIG. 300 300 300 Referring to, the ultrasonic arraymay be superimposed on a plurality of pixels P. The ultrasonic arraymay include a plurality of ultrasonic generators, each of which is superimposed on one of the plurality of pixels. The plurality of pixels P may be arranged in a matrix shape. The ultrasonic arraymay include a plurality of pixel columns PC and a plurality of pixel rows PR. The ultrasonic generators being superimposed on one of the plurality of pixels may be arranged in a rectangular shape.

A pixel column PC is defined as a plurality of ultrasonic generators arranged along the first direction (x). The plurality of pixel rows PR may be arranged to be spaced apart along the second direction (y).

A pixel row PR is defined as a plurality of ultrasonic generators arranged along the second direction (y). Moreover, the plurality of pixel rows PR may be arranged to be spaced apart along the first direction (x).

220 220 A scan signal for selecting a coding row from the plurality of pixel rows PR may be transmitted through at least one of the plurality of second conductive lines. Therefore, each of the plurality of second conductive linesmay include a material having a low resistance to minimize a delay in signal transmission and signal conversion.

210 220 A bias voltage pursuant to the scan signal and the mode changing signal may be applied to the plurality of ultrasonic generators through the plurality of first conductive linesand the plurality of second conductive lines.

390 390 The plurality of CMUT devices CM of the ultrasonic generatormay be configured to generate a plurality of fine ultrasonic waves according to the scan signal and the mode changing signal. Unit-ultrasonic waves generated by the ultrasonic generatormay be a synthesis of the plurality of fine ultrasonic waves generated by the plurality of CMUT devices CM. The plurality of unit-ultrasonic waves may be synthesized to generate a single amplitude-modulated ultrasonic wave.

4 FIG. 390 is a sectional view of a portion of an ultrasonic generator.

4 FIG. 310 320 330 Referring to, the CMUT device CM may include an insulation film, a membraneand an electrode pad.

310 100 The insulation filmmay cover the substrate.

320 310 The membranemay cover the insulation film.

310 320 310 320 310 320 310 310 320 A recess covered by the insulation filmand the membranemay be defined. The recess may be interposed between the insulation filmand the membraneand may have a predetermined depth. The recess may be a sealed space S defined by the insulation filmand the membrane. The recess may be an area caved in by a predetermined depth from one surface of the insulation film. Therefore, the sealed space S may be a three-dimensional space sealed by the insulation filmand the membrane.

320 In an embodiment of the present disclosure, the sealed space S may be maintained in vacuum. The sealed space S may reduce a deformation and air resistance caused by vibrations of the membrane. That is, keeping the sealed space S in the vacuum state may improve the conversion efficiency between electrical energy and acoustic energy.

330 320 330 220 The electrode padmay be disposed on the membrane. The electrode padmay be electrically connected to one of the plurality of second conductive lines.

310 210 220 210 220 The insulation filmmay be interposed between one of the plurality of first conductive linesand one of the plurality of second conductive lines. The one of the plurality of first conductive linesand the one of the plurality of second conductive linesmay be spaced apart along the third direction (z).

310 310 310 330 210 330 220 The insulation filmmay have a predetermined thickness. The insulation filmmay include a material having a predetermined permittivity. The insulation filmmay function as a capacitor between the electrode padand one of the plurality of first conductive lines. The electrode padmay be connected with the second conductive lines.

100 210 310 210 In an embodiment of the present disclosure, the substratemay include silicon. Each of the plurality of first conductive linesmay include a conductive material. The insulation filmmay include a material that is highly adhesive to one of silicon and the first conductive lines.

210 100 310 100 210 210 100 310 100 In an embodiment of the present disclosure, the plurality of first conductive linesmay be disposed on the substrate. Although not illustrated, the insulation filmmay be arranged to be alternatingly in contact with the substrateand the first conductive lines. That is, the plurality of first conductive linesmay be arranged on one surfaced of the substrate, and the insulation filmmay be arranged to cover the other surface of the substrate. It shall be appreciated however that this is merely an example and the present disclosure is not limited to this example.

320 320 310 320 320 310 The membranemay include a semiconductor material. Moreover, the membranemay be a film that vibrates according to charging and discharging of electrostatic charge stored in a capacitor. Since the sealed space S is formed by having the insulation filmcovered by the membrane, it is preferable that the membraneincludes a material that is readily coupled with the insulation filmto seal the sealed space S from the outside.

320 310 When the bias voltage applied to the ultrasonic generators is a pull-in voltage, the membranemay be deformed by the vibrations in the third direction (z) and make contact with the insulation film, which is the bottom surface of the sealed space S.

320 The depth of the sealed space S may be designed such that a proper pull-in voltage Vpi is determined by considering the detection sensitivity of ultrasonic waves and the physical properties of the membrane. The depth of the sealed space S may be the length of the sealed space S measured in the third direction (z).

2 2 4 FIGS.A,B and 320 390 320 Referring to, each of the plurality of recesses may be a CMUT device CM. The plurality of recesses may be defined by a single membrane. Each of the plurality of ultrasonic generatorssuperimposed on a plurality of pixels may include at least one recess defined by a single membrane.

4 FIG. 330 330 320 330 330 220 220 330 Referring to, the electrode padmay function as a common electrode for apply a bias voltage to the plurality of CMUT devices CM. The electrode padmay be disposed on one surface of the membrane. The electrode padmay include an elastic material. The electrode padmay be in contact with at least one of the plurality of second conductive lines. Therefore, the scan signal applied to the second conductive linesmay be transferred to the plurality of CMUT devices CM via the electrode pad. That is, it is possible to have the same scan signal transferred to the plurality of CMUT devices CM.

320 330 In an embodiment of the present disclosure, the membraneand the electrode padmay be a single element that is not distinguishable from each other, unlike the above description.

5 a FIG. 320 310 When a pull-in voltage Vpi (see) is applied to the CMUT device CM, the membranemay be deformed and make contact with the insulation film, which is the bottom surface of the sealed space S. That is, the pull-in voltage Vpi may be a collapse state voltage of the CMUT device CM. In the present specification, such a CMUT device CM is defined as a deformed CMUT device.

330 320 390 330 320 220 The electrode padis configured to be capable of absorbing the deformation of the membraneoccurred when the operation mode of the ultrasonic generator, i.e., the CMUT device CM, is changed to a pull-in mode or a normal mode. Moreover, the electrode padmay be elastic enough to restrain the deformation of the membranedescribed above from being transferred to the plurality of second conductive lines.

210 210 The first conductive linesmay be configured to function as an electrode for applying a bias voltage to the plurality of CMUT devices CM. Moreover, the mode changing signal may be applied to the plurality of CMUT devices CM via the plurality of first conductive lines. That is, it is possible to have the same mode changing signal applied to the plurality of CMUT devices CM.

390 390 Accordingly, the plurality of CMUT devices CM of the ultrasonic generatormay be driven in an identical fashion depending on the scan signal and the mode changing signal. That is, the plurality of CMUT devices CM of the ultrasonic generatorsmay be understood as a single virtual CMUT device of which the operation mode is determined depending on the scan signal or the mode changing signal. Moreover, changing the scan signal and the mode changing signal may result in a change of the operation mode of each of the plurality of ultrasonic generators.

390 The operation mode of the ultrasonic generatormay be one of the normal mode and the pull-in mode.

5 FIG.A is a graphical illustration of the relations between the bias voltage Bias (V) applied to a CMUT device CM and the capacitance C0(pF) of the CMUT device CM.

5 FIG.A Referring to, the capacitance C0(pF) of the CMUT device CM may change differently depending on the direction of change of the bias voltage Bias (V) applied to the CMUT device CM.

390 5 FIG.A Hereinafter, the change of the operation mode of the ultrasonic generatorwill be described with reference to.

390 3900 390 390 390 390 7 FIG. When the ultrasonic generatoris operating in the normal mode, the operation mode of the ultrasonic generatormay be changed to the pull-in mode if the bias voltage Bias (V) is increased to be greater than or equal to the pull-in voltage Vpi. Here, the capacitance C0(pF) of the CMUT device CM of the ultrasonic generatormay vary depending on a pull-in path Ppi. The first natural frequency may be the natural frequency of the ultrasonic generatorof which the operation mode is the normal mode. The ultrasonic generatormay be driven by a drive signal having the same frequency as the first natural frequency. Moreover, the pixel corresponding to the ultrasonic generatorof which the operation mode is the normal mode may function as an active pixel AP (see).

500 As described later in greater detail in connection with the ultrasonic driver, the drive-bias may be for determining the operation mode of the ultrasonic generator, and the drive signal may be for controlling the ultrasonic generator to generate unit-ultrasonic waves.

320 310 320 310 320 310 390 390 390 Specifically, once the bias voltage Bias (V) reaches the pull-in voltage Vpi, the membranemay make contact with the insulation film, which is the bottom surface of the sealed space S, to deform the sealed space S. The pull-in voltage Vpi may be a unique value of the CMUT device CM. When the membranemakes contact with the insulation film, the natural frequency of the CMUT device CM may vary. That is, when the membranemakes contact with the insulation film, the CMUT device CM may operate as a deformed CMUT device. The first natural frequency, which is the natural frequency of the undeformed CMUT device CM, may be different from the second natural frequency, which is the natural frequency of the deformed CMUT device. That is, the natural frequency of the ultrasonic generatorof which the operation mode is the pull-in mode may be the second natural frequency. The ultrasonic generatorof which the operation mode is the pull-in mode may have a different natural frequency from that of the ultrasonic generatorof which the operation mode is the normal mode.

320 390 390 Therefore, in the case where a drive signal having the same frequency as the first natural frequency is applied to the deformed CMUT device, it is not possible to generate ultrasonic wave by vibrating the membrane. The ultrasonic generatorof which the operation mode is the pull-in mode may hardly generate unit-ultrasonic waves in response to the drive signal having the same frequency as the first natural frequency. That is, the pixel P superimposed by the ultrasonic generatoroperating in the pull-in mode may function as an inactive pixel, which does not generate unit-ultrasonic waves.

390 390 390 In the case where the bias voltage Bias (V) is decreased to the pull-out voltage Vpo from the pull-in voltage Vpi when the ultrasonic generatoris operating in the pull-in mode, the operation mode of the ultrasonic generatormay be changed to the normal mode. Accordingly, the ultrasonic generatormay operate based on the drive signal having the same frequency as the first natural frequency.

200 320 320 The bias voltage Bias (V) may be applied to the CMUT device CM via the signal line. The CMUT device CM may function as a capacitor having the capacitance C0(pF) corresponding to the bias voltage Bias (V). When the drive signal, which is an AC signal, is applied to the CMUT device CM, the membranemay vibrate to generate ultrasonic waves. Specifically, if the frequency of the drive signal is identical to the natural frequency of the CMUT device CM, the CMUT device CM may resonate to generate unit-ultrasonic waves. The bias voltage may be determined such that the CMUT device CM has a proper capacitance for allowing the membraneto vibrate.

390 390 390 In the case where the bias voltage smaller than the pull-in voltage Vpi is applied to the ultrasonic generator, the ultrasonic generatormay operate in the normal mode. Moreover, the pixel P corresponding to the ultrasonic generatoroperating in the normal mode may function as an active pixel, which is capable of generating ultrasonic waves.

390 As described above, based on the bias voltage, the operation mode of the ultrasonic generatormay be converted from one of the normal mode and the pull-in mode to the other of the normal mode and the pull-in mode.

390 320 When the bias voltage increases to the pull-in voltage, the operation mode of the ultrasonic generatormay be changed to the pull-in mode. Then, when the bias voltage decreases again to become smaller than the pull-out voltage Vpo, the balance between the restitution of the membraneand the electrostatic force of electrostatic charge may be restored to change the operation mode of the ultrasonic generator back to the normal mode.

320 310 390 320 390 When the operation mode of the ultrasonic generator is changed to the pull-in mode, there may be a static friction force between the membraneand the insulation filmof the ultrasonic generator. In other words, in order to recover the original shape of the membraneand change the operation mode of the ultrasonic generator back to the normal mode, the difference between the bias voltage and the pull-in voltage Vpi needs to be sufficient enough to overcome the aforementioned static friction force. In the case where the difference between the bias voltage and the pull-in voltage Vpi is not sufficient enough to overcome the static friction force, the operation mode of the ultrasonic generatormay be maintained in the pull-in mode.

With respect to a predetermined bias voltage, the capacitance C0(pF) of the CMUT device CM of the ultrasonic generator may vary based on one of the pull-in path Ppi and the pull-out path Ppo. Specifically, although the same bias voltage Bias (V) is applied to the ultrasonic generator, the capacitance C0(pF) of the CMUT device CM may vary based on the pull-out path Ppo if the operation mode of the ultrasonic generator is the pull-in mode, and the capacitance C0(pF) of the CMUT device CM may vary based on the pull-in path Ppi if the operation mode of the ultrasonic generator is the normal mode.

While the operation mode of the ultrasonic generator is the pull-in mode and the bias voltage Bias (V) is decreasing (Ppo) to the pull-out voltage Vpo, the capacitance C0(pF) of the CMUT device CM of the ultrasonic generator corresponding to the predetermined bias voltage may be a first value.

While the operation mode of the ultrasonic generator is the normal mode and the bias voltage Bias (V) is increasing (Ppo) to the pull-in voltage Vpi, the capacitance C0(pF) of the CMUT device CM of the ultrasonic generator corresponding to the predetermined bias voltage may be a second value.

The first value may be greater than the second value. In other words, the capacitance C0(pF) of the CMUT device CM of the ultrasonic generator may be greater when the operation mode of the ultrasonic generator is the pull-in mode than when the operation mode of the ultrasonic generator is the normal mode.

320 310 In the case where the bias voltage becomes smaller than or equal to the pull-out voltage Vpo, the membranemay overcome the static friction force and be separated from the insulation film. That is, the pull-out voltage Vpo may be a voltage for restoring the operation mode of the CMUT device CM to the normal state.

In the present specification, a primary bias voltage means a bias voltage having a tendency of increasing from a voltage that is smaller than the pull-out voltage Vpo to a voltage that is greater than the pull-out voltage Vpo.

390 390 In the case where the bias voltage becomes smaller than the pull-in voltage Vpi, the operation mode of the ultrasonic generatormay be maintained in the pull-in mode until the pull-out voltage Vpo is reached. Moreover, the capacitance C0(pF) of the CMUT device CM may vary based on the pull-out path Ppo. That is, the operation mode of the ultrasonic generatorsmay be determined according to the primary bias voltage and the secondary bias voltage.

5 FIG.B 5 FIG.C andillustrate the operation of the ultrasonic generator according to the same magnitude of primary bias voltage and secondary bias voltage.

5 5 FIGS.B andC In, the pull-in voltage of the ultrasonic generator may be 50 V, and the pull-out voltage of the ultrasonic generator may be 35 V. Hereinafter, the operation mode of the ultrasonic generator will be described when the primary bias voltage and the secondary bias voltage are both 40 V.

5 FIG.B 390 Referring to, when the bias voltage increases to be greater than the pull-out voltage Vpo and smaller than the pull-in voltage Vpi, the operation mode of the ultrasonic generatormay be maintained in the normal mode.

In the present specification, a primary bias voltage means a bias voltage having a tendency of increasing from a voltage that is smaller than the pull-out voltage Vpo to a voltage that is greater than the pull-out voltage Vpo.

In the present specification, a secondary bias voltage means a bias voltage having a tendency of decreasing from a voltage that is greater than the pull-in voltage Vpi to a voltage that is smaller than the pull-in voltage Vpi.

5 FIG.C 390 Referring to, when the secondary bias voltage that is greater than the pull-out voltage Vpo and smaller than the pull-in voltage Vpi is applied, the operation mode of the ultrasonic generatormay be maintained in the pull-in mode.

390 In short, even though the bias voltage is the same magnitude, the operation mode of the ultrasonic generatormay vary depending on whether the bias voltage is a primary bias voltage or a secondary bias voltage.

390 390 390 That is, even if the bias voltage applied to the ultrasonic generatoroperating in the pull-in mode becomes smaller than the pull-in voltage Vpi, the operation mode of the ultrasonic generatormay be maintained in the pull-in mode if the bias voltage applied to the ultrasonic generatoris a secondary bias voltage.

390 390 In other words, as long as the bias voltage is properly adjusted, the operation mode of the ultrasonic generatormay be maintained even if at least one of the mode voltage and the scan voltage is changed. The operation mode of the ultrasonic generatormay correspond to data stored in the pixel.

6 FIG. illustrates an exemplary configuration of a pixel coder in accordance with an embodiment of the present disclosure.

6 FIG. 400 410 420 430 440 450 460 Referring to, the pixel codermay include an initialization driver, a scanline setter, a mode line setter, a pull-in coder, a timing controller, a pixel reset unitand a coding control center CS.

400 301 300 390 390 301 The pixel codermay be configured to generate the coding arrayby coding each of the plurality of pixels P of the ultrasonic arrayso that a operation mode of each of the plurality of pixels P may be a contrasting binary operation mode of the ultrasonic generator. The term “binary operation mode,” as used in the present specification, may be interpreted as meaning that the operation mode may be determined as one of the normal mode and the pull-in mode. The binary operation mode of the ultrasonic generatormay be one of the normal mode and the pull-in mode. The coding arraymay include an active pixel and an inactive pixel.

420 220 420 220 430 210 430 210 The scanline settermay electrically connected selectively with at least one of the plurality of second conductive lines. That is, the scanline settermay be short-circuited or opened to each of the plurality of second conductive linesaccording to a control signal received from the coding control center CS. Similarly, the mode line settermay electrically connected selectively with at least one of the plurality of first conductive lines. The mode line settermay be short-circuited or opened to each of the plurality of first conductive linesaccording to the control signal received from the coding control center CS.

410 440 450 460 210 220 420 430 The initialization driver, the pull-in coder, the timing controllerand the pixel reset unitmay each receive the control signal generated by the coding control center CS and transmit electrical signals to the first conductive linesand the second conductive linesthrough the scanline setterand the mode line setter.

410 210 220 390 The initialization drivermay be configured to apply an initialization signal to the first conductive linesand the second conductive linesto initialize the operation mode of the ultrasonic generatorsto the normal mode.

410 200 When a coding start signal is applied to the coding control center CS, the coding control center CS may control the initialization driverto apply the initialization signal to the signal line.

410 210 220 210 220 The initialization drivermay be configured to apply the initialization signal to the first conductive linesand the second conductive lines. The initialization signal may include a first partial setting signal and a second partial setting signal. The first partial setting signal may be simultaneously applied to the plurality of first conductive lines. The second partial setting signal may be simultaneously applied to the plurality of second conductive lines.

390 A setting voltage Vs may be the potential difference between the first partial setting voltage Vs1 of the first partial setting signal and the second partial setting voltage Vs2 of the second partial setting signal. The setting voltage Vs may be a primary bias voltage satisfying the condition expressed in (1) below. The setting voltage Vs may be simultaneously applied to the plurality of ultrasonic generators.

In condition (1), Vpo may be the pull-out voltage, and Vpi may be the pull-in voltage. Vs may be the setting voltage, whereas Vs1 may be the first partial setting voltage, and Vs2 may be the second partial setting voltage.

390 390 Referring to condition (1), since the setting voltage Vs that is lower than the pull-in voltage Vpi is applied to the ultrasonic generatoras the primary bias voltage, the operation mode of the ultrasonic generatormay be set as the normal mode. In other words, the operation mode of the ultrasonic generators to which the initialization signal is applied may be the normal mode.

300 450 450 420 430 440 Once the initialization is complete for the ultrasonic array, the coding control center CS may transmit a pull-in coding signal to the timing controller. Based on the pull-in coding signal, the timing controllermay control the scanline setter, the mode line setterand the pull-in coderto code some of the plurality of pixels P, coded with the normal mode, with the pull-in mode.

420 220 420 300 The scanline settermay be configured to select one of the second conductive linesas a scan line SL for transmitting the scan signal. The scanline settermay be configured to select the pixel row PR of the ultrasonic arraycorresponding to the scan line SL as a coding row.

220 200 7 FIG. In an embodiment of the present disclosure, the second conductive linesmay be successively selected one by one along a predetermined direction as the scan line SL. That is, all of the second conductive linesmay be selected one by one successively as the scan line SL. The plurality of pixels corresponding to the scan line SL may be selected as a coding row CR (see).

7 FIG. 301 illustrates an exemplary generation of amplitude-modulated ultrasonic waves AMU from the coding array.

7 FIG. 430 210 430 Referring to, the mode line settermay be configured to select at least one of the plurality of first conductive linesas a mode changing line MSL. The mode changing line MSL may be a first conductive line for transmitting the mode changing signal. The mode changing signal may convert the operation mode of the ultrasonic generator superimposed on a pixel P. The mode line settermay be configured to select a pixel column corresponding to the mode changing line MSL as a coding column.

450 430 430 210 210 7 FIG. Information about the pixel column including a coding target pixel, among the pixels of the coding row selected by the timing controller, may be transmitted to the mode line setter. The mode line settermay be configured to select the first conductive lineof the plurality of first conductive linesthat corresponds to the pixel column as the mode changing line MSL. The plurality of pixels corresponding to the mode changing line MSL may be set as a single coding column CC (see).

440 Once the scan line SL and the mode changing line MSL are selected, the pull-in codermay apply the scan signal and the mode changing signal to the scan line SL and the mode changing line MSL, respectively. A scan voltage may be the voltage of the scan signal. A mode voltage may be the voltage of the mode changing signal.

390 390 440 The coding target pixel may be a pixel where the coding row and the coding column intersect. The operation mode of the ultrasonic generatorsuperimposed on the coding target pixel may be changed to the pull-in mode by the bias voltage that is higher than the pull-in voltage Vpi. The bias voltage applied to the ultrasonic generatormay be a potential difference between the mode voltage and the scan voltage Vscan. That is, the pull-in codermay be configured to perform a pull-in coding operation, in which a pixel P coded in the normal mode is coded in the pull-in mode.

In an embodiment of the present disclosure, when the mode voltage Vmode and the scan voltage satisfy the below conditions (2) to (4), a bias voltage that is greater than the pull-in voltage Vpi may be applied to the ultrasonic generator superimposed on the coding target pixel. That is, the operation mode of the ultrasonic generator superimposed on the coding target pixel among the ultrasonic generators superimposed on the coding row may be changed to the pull-in mode. On the other hand, the operation mode of the ultrasonic generator not corresponding to the coding target pixel among the ultrasonic generators superimposed on the coding row may be kept in the normal mode.

In conditions (2) and (4), Vs may be a setting voltage, and Vscan may be a scan voltage, and Vmode may be a mode voltage.

450 450 Once the pull-in coding operation is complete for the selected coding row CR and coding column CC, a next pixel row PR may be selected by the timing controlleras a new coding row. Moreover, among the pixels included in the new coding row, a pixel column including the coding target pixel may be selected as a new coding column by the timing controller. Accordingly, the second conductive line and the first conductive line corresponding to the new coding row and the new coding column may be selected as a new scan line SL and a new mode changing line MSL, respectively.

Then, the scan voltage and the mode voltage may be applied, respectively, to the new scan line SL and the new mode changing line MSL. Accordingly, the operation mode of the ultrasonic generator corresponding to the new coding target pixel may be set to the pull-in mode.

450 300 The timing controllermay be configured to successively select the plurality of pixel rows one by one and then selectively perform the pull-in coding operation for some of the pixels belonging to the pixel row. Accordingly, every pixel P of the ultrasonic arraymay be coded to have data corresponding to one of the normal mode and the pull-in mode.

Here, the operation mode of the pull-in pixel that has been already coded in the pull-in mode in the previous coding row CR while the pull-in coding operation is performed for the selected coding row CR may be maintained without changing.

The scan voltage Vscan and the mode voltage Vmode set in the pull-in coding operation for the previous coding row may not be maintained in the pull-in coding operation for another coding row that is selected later. Therefore, the operation mode of the pull-in pixel may be maintained, regardless of the change of the bias voltage for the pull-in pixel.

In an embodiment of the present disclosure, when the scan voltage Vscan, the mode voltage Vmode and the setting voltage Vs satisfy the below condition (5), the operation mode of the pull-in pixel that has been already coded in the pull-in mode may be maintained.

301 300 Based on the setting voltage, scan voltage and mode voltage satisfying the above condition, the pixel P coded in the normal mode may be coded in the pull-in mode. Accordingly, generated is a coding arraythat includes active pixels AP coded in the normal mode and inactive pixels IAP coded in the pull-in mode based on the ultrasonic array.

390 For instance, in the case where the pull-in voltage of the CMUT device of the ultrasonic generatoris 50 V and the pull-out voltage is 30 V, the pixel P may be coded in the pull-in mode if the setting voltage, the scan voltage and the mode voltage are, respectively, 35 V, −10 V and 45 V. However, this is merely an example, and it shall be appreciated that the setting voltage, the scan voltage and the mode voltage of the present disclosure are not limited to the described example.

301 460 301 301 In the present specification, a pixel map may refer to information relating to the distribution of the active pixels AP and inactive pixels IAP of the coding array. The coding control center CS may be configured to control the pixel reset unitto reset the active pixels AP and inactive pixels IAP of the coding array. After the active pixels AP and inactive pixels IAP of the coding arrayare reset, the pixel map may be changed.

460 420 430 200 301 When a pixel reset signal is detected, the pixel reset unitmay control the scanline setterand the mode line setterto ground the signal line. Accordingly, the active pixels AP and the inactive pixels IAP of the coding arraymay be reset to a pre-coding state. Thereafter, a coding array corresponding to the changed pixel map may be generated.

500 301 301 In an embodiment of the present disclosure, the ultrasonic drivermay be configured to drive the coding array. The coding arraymay generate amplitude-modulated ultrasonic waves AMU. The wavefront of the amplitude-modulated ultrasonic waves AMU may be deformed. The amplitude-modulated ultrasonic waves AMU may be a synthesis of a plurality of unit-ultrasonic waves generated by the plurality of ultrasonic generators. Each of the plurality of ultrasonic generators may be superimposed on an active pixel AP.

500 510 520 In an embodiment of the present disclosure, the ultrasonic drivermay include a drive setting unitand a driving unit.

510 301 301 The drive setting unitmay be configured to apply a drive-bias to the coding arrayto control the bias voltages applied to the plurality of ultrasonic generators of the coding arrayto be identical with each other.

Since the scan voltage Vscan and the mode voltage Vmode are simultaneously applied to the plurality of ultrasonic generators corresponding to the coding column CC, the bias voltages applied to the plurality of ultrasonic generators may be different from each other. When the bias voltages applied to the plurality of ultrasonic generators are different from each other, the intensities of the ultrasonic waves generated at the plurality of active pixels corresponding to the plurality of ultrasonic generators may be different from each other. Accordingly, the wavefront of the amplitude-modulated ultrasonic waves may be distorted.

510 210 220 The drive setting unitmay be configured to apply a drive-bias satisfying condition (6) described below to the first conductive linesand control the second conductive linesto be grounded.

Vpo may be a pull-out voltage, and Vpi may be a pull-in voltage. Vd may be a drive-bias.

That is, if the drive-bias is smaller than the pull-in voltage and greater than the pull-out voltage, the operation mode of the ultrasonic generator corresponding to the pull-in pixel may be maintained in the pull-in mode.

520 301 The driving unitmay be configured to apply an AC drive signal to the coding arrayand control the ultrasonic waves to be generated at an active pixel AP. By successively applying the drive-bias and the drive signal to the ultrasonic generator corresponding to the active pixel AP, the electrostatic charge accumulated in the CMUT device CM of the ultrasonic generator may vibrate to generate ultrasonic waves.

The frequency of the AC signal may be the same as the first natural frequency. The first natural frequency may be the natural frequency of the CMUT device CM operating in the normal mode. The first natural frequency may be different from the second natural frequency, which is the natural frequency of the CMUT device CM of the ultrasonic generator operating in the pull-in mode. Therefore, the CMUT device CM of the ultrasonic generator of which the operation mode is the pull-in mode may not be operated by the drive signal.

That is, while ultrasonic waves having the largest acoustic energy are generated in response to the drive signal at the active pixels corresponding to the ultrasonic generator of which the operation mode is the normal mode, the ultrasonic waves may be hardly generated at the inactive pixels corresponding to the ultrasonic generator of which the operation mode is the pull-in mode.

301 The amplitude-modulated ultrasonic waves AMU may be generated by synthesizing the plurality of unit-ultrasonic waves generated at the plurality of active pixels AP of the coding array.

7 FIG. 301 Referring to, once the drive signal is applied, the coding arraymay generate the amplitude-modulated ultrasonic waves in which the wavefront may be shaped correspondingly to the pixel map.

When the operation mode of the ultrasonic generator corresponding to the pixel is the normal mode, the pixel may function as the active pixel AP. The unit-ultrasonic waves may be generated at the active pixel AP in response to the AC drive signal.

When the operation mode of the ultrasonic generator corresponding to the pixel is the pull-in mode, the pixel may function as the inactive pixel IAP. The unit-ultrasonic waves may not be generated at the inactive pixels IAP in response to the AC drive signal.

301 The active pixel AP may be a point source of the unit-ultrasonic wave, which is a spherical wave. That is, the coding arraymay include a plurality of point sources that correspond to the pixel map and configured to generate a plurality of unit-ultrasonic waves. The sound pressure of each of the plurality of CMUT devices may be generated in the form of unit-ultrasonic waves.

301 The wavefront of the amplitude-modulated ultrasonic waves AMU may be determined by the distribution of sound pressure. The wavefront of the amplitude-modulated ultrasonic waves AMU may be shaped to bend downwardly around the inactive pixels IAP and to bend upwardly around the active pixels AP. Accordingly, the coding arraymay generate the amplitude-modulated ultrasonic waves AMU corresponding to the pixel map.

390 The shape of the wavefront of the amplitude-modulated ultrasonic waves AMU may be determined by the pixel map. Specifically, the operation mode of the ultrasonic generatormay be changed according to the scan voltage Vscan, the mode voltage Vmode and the setting voltage Vs. Moreover, the pixel map may be changed in real time according to the scan signal and the mode changing signal. Therefore, a plurality of amplitude-modulated ultrasonic waves AMU having different shapes of wavefront according to the scan signal and the mode changing signal may be generated.

600 400 301 600 301 301 For example, the waveform controllermay be configured to control the pixel coderto change the coding arrayaccording to the wavefront information. Moreover, the waveform controllermay control the ultrasonic driver to generate amplitude-modulated ultrasonic waves according to the changed coding array. If the coding arrayis continuously changed, the wavefront of the amplitude-modulated ultrasonic waves may be also continuously changed. That is, the present disclosure may allow the user to generate the amplitude-modulated ultrasonic waves of which the wavefront is continuously changed with time.

8 FIG. 2000 illustrates an exemplary configuration of an ultrasonic apparatusin accordance with an embodiment of the present disclosure.

1200 1200 1000 1200 1 7 FIGS.to 1 7 FIGS.to In the ultrasonic apparatus in accordance with an embodiment of the present disclosure, the amplitude-modulated ultrasonic waves generated by the spatial ultrasound modulatormay be used as incident waves for ultrasonic processing of a target object. The spatial ultrasound modulatoris substantially the same as the spatial ultrasound modulatordescribed with reference to. Hereinafter, the spatial ultrasound modulatorwill be described with reference to the drawing symbols used in.

8 FIG. 2000 1100 1200 1300 Referring to, the ultrasonic apparatusin accordance with an embodiment of the present disclosure may include a wavefront information setter, a spatial ultrasound modulatorand a response detection unit.

110 The wavefront information settermay be configured to set wavefront information corresponding to incident waves, which are spatially modulated ultrasonic waves incident on a target object.

1200 301 1200 1200 The spatial ultrasound modulatormay generate a coding arraybased on the wavefront information. The spatial ultrasound modulatormay generate amplitude-modulated ultrasonic waves having the wavefront corresponding to the wavefront information. The amplitude-modulated ultrasonic waves generated by the spatial ultrasound modulatormay be used as incident waves.

1300 The response detection unitmay be configured to detect a response of the target object for ultrasonic processing to the incident waves.

1100 The wavefront information settermay be configured to generate a pixel map corresponding to the wavefront information. The wavefront information may be inputted in real time by the user. Moreover, the wavefront information may be included in a pre-stored database. The pixel map may be modified according to the shape of the target object, the characteristics of the target object and the purpose of ultrasonic processing.

1100 In an embodiment of the present disclosure, the wavefront information settermay include a data storage and an array setter.

The data storage may be configured to store reference data. The reference data may include a plurality of pixel maps and matching information between wavefronts of a plurality of reference amplitude-modulated ultrasonic waves. The wavefront of each of the plurality of reference amplitude-modulated ultrasonic waves may correspond to one of the plurality of pixel maps. Moreover, each of the plurality of reference amplitude-modulated ultrasonic waves may be amplitude-modulated ultrasonic waves generated by a sample array.

The array setter may be configured to select one of a plurality of sample arrays as a set array. The set array may be a sample array of the plurality of sample arrays that corresponds to the shape of wavefront of the reference amplitude-modulated ultrasonic waves corresponding to the incident waves.

The data storage may be configured to store pixel-wavefront matching information with respect to the pixel map of the sample array and the wavefront of the reference amplitude-modulated ultrasonic waves.

The pixel-wavefront matching information may include information about troughs and peaks of the reference amplitude-modulated ultrasonic waves and the separation distance between the plurality of pixels constituting the sample array.

Based on the pixel-wavefront matching information, the distribution of the operation modes of a plurality of ultrasonic generators of the set array. The set array may be transferred to the coding control center CS.

301 301 Accordingly, the coding arraycorresponding to the set array may be generated. By having a drive signal applied to the coding array, amplitude-modulated ultrasonic waves having a predetermined wavefront shape may be generated.

1200 1000 1 FIG. As mentioned, the spatial ultrasound modulatorconfigured for generating amplitude-modulated ultrasonic waves AMU has substantially identical configurations as the spatial ultrasound modulatorillustrated inand thus will not be redundantly described.

1200 1200 1200 The spatial ultrasound modulatormay be couple to a housing configured with a flexible material. The spatial ultrasound modulatormay modify the coding array according to the shape of the target object. By adjusting the shape of the housing to correspond to the shape and curvature of the target object, the incident waves generated by the spatial ultrasound modulatormay be readily focused at the target object.

2000 For example, the target object may be an object for testing for an imaging of internal defect or shape using amplitude-modulated ultrasonic waves. Moreover, the target object may be a living body in which nerves stimulated by the amplitude-modulated ultrasonic waves are arranged. In other words, the ultrasonic apparatusof the present disclosure may be used as an ultrasonic inspection apparatus and ultrasonic neural stimulation apparatus.

1300 1300 1300 The response detection unitmay be adapted according to the characteristics of the target object. For example, if the target object is a living body arranged with nerves stimulated by the amplitude-modulated ultrasonic waves, the response detection unitmay be a device for detecting and storing operational characteristics, including at least one of the form, periodicity and magnitude of the response. Moreover, the response detection unitmay be a device for comparing the operation and condition before and after neural stimulation by the amplitude-modulated ultrasonic waves.

1300 1300 1300 For instance, the response detection unitmay be a device for detecting a biological signal generated in response to the amplitude-modulated ultrasonic waves in a living body in which nerves are arranged. If the biological signal is an electrical signal, the response detection unitmay be a device capable of detecting at least one of voltage and current. If the biological signal is a chemical substance including hormones, the response detection unitmay be a device capable of detecting the composition and concentration of the chemical substance.

1300 1200 1200 1300 1300 1200 1200 In an embodiment of the present disclosure, the response detection unitmay not be coupled with the spatial ultrasound modulatorbut arranged to be separated from the spatial ultrasound modulator. Specifically, if the response detection unitis a device for detecting and storing the operational characteristics, the response detection unitmay not be coupled with the spatial ultrasound modulatorbut arranged to be separated from the spatial ultrasound modulator.

1300 1300 1200 On the other hand, if the response detection unitis a device for detecting electrical or chemical signals, the response detection unitmay be connected with the spatial ultrasound modulatorto be linked to the ultrasonic characteristics and analyze the detected signals.

1300 1200 1300 1300 1200 1300 1200 In an embodiment of the present disclosure, the response detection unitmay be coupled and electrically connected to the spatial ultrasound modulator. Specifically, in the case where the response detection unitis a device for comparing the operation and condition before and after neural stimulation by the amplitude-modulated ultrasonic waves, the response detection unitmay be electrically connected to the spatial ultrasound modulator. Moreover, the response detection unitmay be configured to analyze the biological signal based on the characteristics of the amplitude-modulated ultrasonic waves generated by the spatial ultrasound modulator.

1300 1300 In an embodiment of the present disclosure, if the target object is an object for testing for an internal defect or shape using amplitude-modulated ultrasonic waves, the response detection unitmay perform the function of detecting reflected waves generated inside the target object in response to the amplitude-modulated ultrasonic waves. The response detection unitmay be a device for collecting information about the inside of the target object using the reflected waves.

For example, the reflected waves generated inside the target object in response to the amplitude-modulated ultrasonic waves may be detected by the plurality of CMUT devices CM of the spatial ultrasound modulator. The reflected waves detected by the plurality of CMUT devices CM may be used for collecting the information about the inside of the target object. As the integration density of the CMUT device CM increases, the focusing resolution for the reflected waves generated inside the target object may be improved, and the information about the inside of the target object may be collected more accurately.

390 390 Specifically, in the course of generating amplitude-modulated ultrasonic waves, which are incident waves, the ultrasonic generatormay convert electrical energy to acoustical energy, i.e., ultrasonic waves. By contrast, in the course of detecting reflected waves, the ultrasonic generatormay convert the acoustical energy of the reflected waves to electrical energy. In other words, if the integration density of the CMUT device CM is increased, not only the focusing resolution but also the detection resolution of the reflected waves may be improved.

301 With the present disclosure, by modifying the coding arrayby adjusting the setting voltage, scan voltage and mode voltage, the wavefront of the incident waves being incident at the target object may be deformed in real time.

9 9 FIGS.A toF illustrate a method of generating amplitude-modulated ultrasonic waves.

9 9 FIGS.A toF 1 9 FIGS.to Hereinafter, the method of generating amplitude-modulated ultrasonic waves ofwill be described with reference to the drawing symbols used in.

9 FIG.A Referring to, the method of generating amplitude-modulated ultrasonic waves in accordance with an embodiment of the present disclosure may include step 1, step 2, step 3 and step 4.

In step 1, an ultrasonic array may be initialized to a setting voltage Vs, and the operation mode of a plurality of ultrasonic generators may be changed to a normal mode NM. The ultrasonic array may include a plurality of pixel rows and a plurality of pixel columns. Each pixel row PR and pixel column PC may include a plurality of ultrasonic generators. Each of the plurality of ultrasonic generators may be superimposed on one of the plurality of pixels.

210 220 390 Specifically, a first partial setting signal having a first partial setting voltage may be applied to a first conductive line. A second partial setting signal having a second partial setting voltage may be applied to a second conductive line. A setting voltage Vs may be the potential difference between the first partial setting voltage Vs1 of the first partial setting signal and the second partial setting voltage Vs2 of the second partial setting signal. The setting voltage Vs may be applied to the ultrasonic generator.

220 In an embodiment of the present disclosure, a second conductive linemay be grounded, and the setting voltage Vs may be the first partial setting voltage Vs1. In order to change the operation mode of the ultrasonic generator to the normal mode NM, the setting voltage Vs may be determined with a value between a pull-out voltage and a pull-in voltage.

In step 2, the pixel rows may be successively selected one by one as a coding row. Moreover, at least one of the plurality of pixel columns corresponding to a coding target pixel may be selected as a coding column.

9 FIG.B Referring to, in step 3, the operation mode of the ultrasonic generator corresponding to the coding target pixel may be changed to a pull-in mode to generate a coding array. The coding array may include an active pixel and an inactive pixel. An active pixel may be a pixel of which the operation mode of the corresponding ultrasonic generator is coded in the normal mode. An inactive pixel may be a pixel of which the operation mode of the corresponding ultrasonic generator is coded in the pull-in mode. A coding target pixel may be a pixel arranged at an intersection of the coding row and the coding column.

A first natural frequency may be different from a second natural frequency. The first natural frequency may be a natural frequency of the ultrasonic generator of which the operation mode is the pull-in mode. The second natural frequency may be a natural frequency of the ultrasonic generator of which the operation mode is the normal mode. Whenever a coding row is selected, a scan voltage and a mode voltage may be applied to the coding row and the coding column, and the operation mode of the ultrasonic generator corresponding to the coding target pixel may be changed to the pull-in mode.

9 FIG.B 210 1 210 13 14 1 Referring to, the scan voltage Vscan may be applied to one of the plurality of first conductive lines, and a first pixel row PRmay be selected as the coding row. Then, among the plurality of first conductive lines, a third first conductive line and a fourth first conductive line may be selected to mode changing lines MSL. The mode voltage Vmode may be applied to the mode changing lines MSL. The operation mode of the ultrasonic generators superimposed on the third pixel Pand the fourth pixel Pof the first pixel row PRmay be changed to the pull-in mode PIM.

According to an embodiment of the present disclosure, in step 3, if the setting voltage Vs, the scan voltage Vscan and the mode voltage Vmode satisfy the below conditions (2) to (4), the operation mode of the ultrasonic generator that is not superimposed on the coding target pixel among the plurality of ultrasonic generators superimposed on the coding row may be maintained in the normal mode NM.

9 FIG.B 13 14 1 Referring to, a bias voltage greater than the pull-in voltage Vpi may be applied to the ultrasonic generators superimposed on the third pixel Pand the fourth pixel Pof the first pixel row PR. Accordingly, the operation mode of the pertinent ultrasonic generators may be changed from the normal mode NM to the pull-in mode PIM.

11 12 1 On the other hand, a bias voltage smaller than the pull-in voltage Vpi may be applied to the ultrasonic generators superimposed on the first pixel Pand the second pixel Pof the first pixel row PR. Accordingly, the operation mode of the pertinent ultrasonic generators may be maintained in the normal mode NM.

In conditions (2) and (4), Vs may be the setting voltage. Vscan may be the scan voltage, and the Vmode may be the mode voltage.

9 FIG.C 1 2 22 24 2 210 210 Referring to, the first pixel row PRmay be grounded. Then, by having the scan voltage Vscan applied to the first conductive line, the second pixel row PRmay be selected as the coding row. Then, in order to change the operation mode of the ultrasonic generators superimposed on the second pixel Pand the fourth pixel Pof the second pixel row PRto the pull-in mode, the second first conductive line and the fourth first conductive line of the plurality of first conductive linesmay be selected as the mode changing lines MSL. The mode voltage Vmode may be applied to the second first conductive line and the fourth first conductive line of the plurality of first conductive lines.

22 24 2 22 24 2 Here, if the scan voltage Vscan, the mode voltage Vmode and the setting voltage Vs satisfy conditions (2) and (3), a bias voltage greater than the pull-in voltage may be applied to the ultrasonic generators superimposed on the second pixel Pand the fourth pixel Pof the second pixel row PR. Accordingly, the operation mode of the ultrasonic generators superimposed on the second pixel Pand the fourth pixel Pof the second pixel row PRmay be converted from the normal mode NM to the pull-in mode PIM.

21 23 2 21 23 2 On the other hand, a bias voltage lower than the pull-in voltage Vpi may be applied to the first pixel Pand the third pixel Pof the second pixel row PR. Accordingly, the operation mode of the ultrasonic generators superimposed on the first pixel Pand the third pixel Pof the second pixel row PRmay be remained in the normal mode NM.

9 FIG.C 22 24 2 Here, if the scan voltage Vscan, the mode voltage Vmode and the setting voltage Vs satisfy condition (5), the operation mode of the ultrasonic generator corresponding to the pull-in pixel may be maintained in the pull-in mode while the pull-in coding operation for the pertinent coding row is processed. A pull-in pixel may be a pixel coded with a pull-in mode by the pull-in coding operation. In, the second pixel Pand the fourth pixel Pof the second pixel row PRmay each be a pull-in pixel.

2 22 24 Accordingly, while the pull-in coding operation is performed for the second pixel row PR, the operation mode of the ultrasonic generators superimposed on the pull-in pixels P, Palready coded with the pull-in mode may be maintained in the pull-in mode PIM.

9 FIG.D 2 210 3 31 33 3 210 210 Referring to, the second pixel row PRmay be grounded. Then, the scan voltage Vscan may be applied to the first conductive lineto select the third pixel row PRas the coding row. Then, in order to pull-in code the first pixel Pand the third pixel Pof the third pixel row PR, the first line and the third line of the plurality of first conductive linesmay be selected as the mode changing lines MSL. Moreover, the mode voltage Vmode may be applied to the first line and the third line of the plurality of first conductive lines.

31 33 3 31 33 3 Here, if the scan voltage Vscan, the mode voltage Vmode and the setting voltage Vs satisfy conditions (2) and (3), a bias voltage greater than the pull-in voltage may be applied to the first pixel Pand the third pixel Pof the third pixel row PR. Accordingly, the operation mode of the ultrasonic generators superimposed on the first pixel Pand the third pixel Pof the third pixel row PRmay be changed from the normal mode NM to the pull-in mode PIM.

32 34 3 32 34 3 On the other hand, a bias voltage lower than the pull-in voltage Vpi may be applied to the second pixel Pand the fourth pixel Pof the third pixel row PR. Accordingly, the operation mode of the ultrasonic generators superimposed on the second pixel Pand the fourth pixel Pof the third pixel row PRmay be maintained in the normal mode NM.

9 FIG.C 31 33 3 3 31 33 3 As in the case of, the scan voltage Vscan, the mode voltage Vmode and the setting voltage Vs may satisfy conditions (4) and (5). Moreover, a secondary bias voltage smaller than the pull-in voltage Vpi may be applied to the ultrasonic generators superimposed on the first pixel Pand the third pixel Pof the third pixel row PRthat have already been coded in the pull-in mode while the pull-in coding operation is processed for the third pixel row PR. Therefore, the operation mode of the ultrasonic generators superimposed on the first pixel Pand the third pixel Pof the third pixel row PRmay be maintained in the pull-in mode PIM.

9 FIG.E 3 210 4 41 44 4 210 210 Referring to, the third pixel row PRmay be grounded. Then, the scan voltage Vscan may be applied to the fourth first conductive line of the plurality of first conductive linesto select the fourth pixel row PRas the coding row. Then, in order to pull-in code the first pixel Pand the fourth pixel Pof the fourth pixel row PR, the first conductive line and the fourth first conductive line of the plurality of first conductive linesmay be selected as the mode changing lines MSL. Moreover, the mode voltage Vmode may be applied to the first conductive line and the fourth first conductive line of the plurality of first conductive lines.

41 44 4 41 44 4 Here, if the scan voltage Vscan, the mode voltage Vmode and the setting voltage Vs satisfy conditions (2) and (3), a bias voltage greater than the pull-in voltage may be applied to the first pixel Pand the fourth pixel Pof the fourth pixel row PR. Accordingly, the operation mode of the ultrasonic generators superimposed on the first pixel Pand the fourth pixel Pof the fourth pixel row PRmay be changed from the normal mode NM to the pull-in mode PIM.

42 43 4 42 43 4 On the other hand, a bias voltage lower than the pull-in voltage Vpi may be applied to the second pixel Pand the third pixel Pof the fourth pixel row PR. Accordingly, the operation mode of the ultrasonic generators superimposed on the second pixel Pand the third pixel Pof the fourth pixel row PRmay be maintained in the normal mode NM.

9 FIG.D 41 44 4 4 41 44 4 As in the case of, the scan voltage Vscan, the mode voltage Vmode and the setting voltage Vs may satisfy conditions (4) and (5). Accordingly, a secondary bias voltage smaller than the pull-in voltage Vpi may be applied to the ultrasonic generators superimposed on the first pixel Pand the fourth pixel Pof the fourth pixel row PRthat have already been coded in the pull-in mode PIM while the pull-in coding operation is processed for the fourth pixel row PR. Therefore, the operation mode of the ultrasonic generators superimposed on the first pixel Pand the fourth pixel Pof the fourth pixel row PRmay be maintained in the pull-in mode PIM.

9 FIG.F 301 210 220 Referring to, a drive-bias may be applied to the coding array, and the capacitances of the plurality of pixels may be identical to each other. Specifically, since the scan voltage Vscan and the mode voltage Vmode are simultaneously applied to the plurality of ultrasonic generators corresponding to a coding column CC, the bias voltages applied to the plurality of ultrasonic generators may be different from each other. In order to control the bias voltages applied to the plurality of ultrasonic generators to be identical to each other, a drive-bias satisfying condition (6) may be applied to the plurality of first conductive lines, and the second conductive linesmay be grounded.

In condition (6), Vpo may be a pull-out voltage, and Vpi may be a pull-in voltage. Vd may be a drive-bias.

301 Specifically, if the drive-bias is smaller than the pull-in voltage and greater than the pull-out voltage, the operation mode of the ultrasonic generator corresponding to the pull-in pixel of the coding arraymay be maintained in the pull-in mode PIM.

301 301 Then, when the drive signal, which is an AC signal, is applied to the coding array, to which the uniform drive-bias is applied, unit-ultrasonic waves may be generated at the active pixels AP. In the case where the frequency of the drive signal is the same as the first natural frequency, resonance may occur in the active pixels to generate ultrasonic waves having a great energy, and nearly no ultrasonic waves may be generated in the inactive pixels. The amplitude-modulated ultrasonic waves AMU may be generated by the synthesis of the plurality of ultrasonic waves generated in the plurality of active pixels AP of the coding array.

In the method of generating amplitude-modulated ultrasonic waves in accordance with an embodiment of the present disclosure, the plurality of ultrasonic generators may be coded with one of the normal mode and the pull-in mode to generate the coding array. Each of the plurality of ultrasonic generators may include at least one CMUT device. Each ultrasonic array may include a plurality of ultrasonic generators superimposed on one of the plurality of pixels. The coding array may include an active pixel and an inactive pixel.

When the drive signal having the same frequency as the natural frequency of the ultrasonic generator operating in the normal mode is applied to the coding array, unit-ultrasonic waves may be generated in the active pixels only, and no unit-ultrasonic waves may be generated in the inactive pixels. That is, a plurality of amplitude-modulated ultrasonic waves having different shapes of wavefront according to the pixel map may be generated.

3001 The operation mode of the plurality of ultrasonic generators of the coding array may be changed according to the scan voltage, the mode voltage and the setting voltage. Therefore, with the present disclosure, the user may readily change the coding arrayby changing the scan voltage, the mode voltage and the setting voltage. Moreover, with the present disclosure, the user may change the shape of the wavefront of the amplitude-modulated ultrasonic waves AMU by changing the scan voltage, the mode voltage and the setting voltage.

Hitherto, certain preferred embodiments of the present disclosure have been described in detail, but anyone ordinarily skilled in the art to which the present disclosure pertains shall appreciate that there may be a variety of modifications and permutations of the present disclosure without departing from the technical ideas and scopes of the present disclosure that are defined in the appended claims.